POTS (postural tachycardia syndrome) is a chronic form of OI (orthostatic intolerance). Neuropathic POTS is characterized by decreased adrenergic vasoconstriction, whereas hyperadrenergic POTS exhibits increased adrenergic vasoconstriction. We hypothesized that midodrine, an α1-adrenergic receptor agonist, would increase CVR (calf vascular resistance), decrease Cv (calf venous capacitance) and decrease orthostatic tachycardia in neuropathic POTS, but not alter haemodynamics in hyperadrenergic POTS. A total of 20 POTS patients (12 neuropathic and eight hyperadrenergic), ages 12–20 years, participated in this randomized placebo-controlled double-blind cross-over study. Of these subjects, 15 were female. POTS subjects received 2 weeks of treatment with midodrine or placebo, with increased dosing from 2.5 to 10 mg three times daily. Following a 7-day drug-washout period, subjects received the cross-over treatment. HR (heart rate), MAP (mean arterial pressure), Q̇calf (calf blood flow) and CVR were measured supine and during 35° HUT (head-up tilt). Cv was measured supine. In neuropathic POTS, midodrine decreased supine HR, Q̇calf and Cv, while increasing MAP and CVR compared with placebo. During HUT, in neuropathic POTS, midodrine decreased HR, Q̇calf and Cv, while increasing MAP and CVR. In hyperadrenergic POTS, placebo and midodrine both decreased upright HR and increased supine CVR. Placebo also increased supine Cv, compared with midodrine in hyperadrenergic POTS. Therefore midodrine improved postural tachycardia in neuropathic POTS by increasing CVR and decreasing Q̇calf and Cv, whereas these effects were not seen in hyperadrenergic POTS patients who experienced a placebo effect. This suggests that midodrine is probably an effective treatment for neuropathic POTS, but not for hyperadrenergic POTS.
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Research Article|
October 22 2013
A double-blind placebo-controlled cross-over study of the vascular effects of midodrine in neuropathic compared with hyperadrenergic postural tachycardia syndrome
Amanda J. Ross;
Amanda J. Ross
*Department of Behavioral Biology, Johns Hopkins University, Baltimore, MD 21218, U.S.A.
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Anthony J. Ocon;
Anthony J. Ocon
†Department of Physiology, New York Medical College, Valhalla, NY 10595, U.S.A.
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Marvin S. Medow;
Marvin S. Medow
†Department of Physiology, New York Medical College, Valhalla, NY 10595, U.S.A.
‡Department of Pediatrics, New York Medical College, Valhalla, NY 10595, U.S.A.
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Julian M. Stewart
†Department of Physiology, New York Medical College, Valhalla, NY 10595, U.S.A.
‡Department of Pediatrics, New York Medical College, Valhalla, NY 10595, U.S.A.
Correspondence: Dr Julian M. Stewart (email [email protected]).
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Publisher: Portland Press Ltd
Received:
May 09 2013
Revision Received:
August 23 2013
Accepted:
August 27 2013
Accepted Manuscript online:
August 27 2013
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© The Authors Journal compilation © 2014 Biochemical Society
2014
Clin Sci (Lond) (2014) 126 (4): 289–296.
Article history
Received:
May 09 2013
Revision Received:
August 23 2013
Accepted:
August 27 2013
Accepted Manuscript online:
August 27 2013
Citation
Amanda J. Ross, Anthony J. Ocon, Marvin S. Medow, Julian M. Stewart; A double-blind placebo-controlled cross-over study of the vascular effects of midodrine in neuropathic compared with hyperadrenergic postural tachycardia syndrome. Clin Sci (Lond) 1 February 2014; 126 (4): 289–296. doi: https://doi.org/10.1042/CS20130222
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